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The RWA Interdynamic KG-9 Assault Pistol

by Dom on August 30, 2015 | comments

The first time I've seen this gun was in a movie called "Big Trouble in Little China"with Kurt Russell and I love it ever since. The initial design of the gun had several versions with bigger and smaller changes over the years but it, sadly, disappeared and never became a success story. People complained about reliability issues, some said it is impractical, but almost everyone knows this gun's distinctive shape from a video game, movie, rap video or news reels.

The KG-9 originated from the Interdynamic AB MP-9. The Swedish company aimed the MP-9 for the M/LE market with little success so they figured that they will try the civilian market in the USA instead. Interdynamic USA was born and the MP-9 was renamed to KG-9 for the North American market.

This version had to comply with US laws so it had semi-auto firing mode only, but it was too easy to convert it to full auto because of its open bolt system and probably this is why it became popular amongst criminals. Later, the open bolt system was changed to closed bolt to make illegal conversions harder and the KG-9 got renamed again to KG-99. Later on, Intratec picked up manufacturing (after Interdynamic USA closed its doors) under the infamous name Tec-9, probably this model is the gun's most known name. I don't want to get into the whole school shooting issue, let's just say some historical events affected the career of our KG-9/Tec-9 in a very negative way.

There were a couple of efforts to revive sales by modifying/renaming the gun in order to meet new laws, but without too much of a success. Let's see how much of a success RWA created by bringing their version of the KG-9 to the airsoft world.

I am not a fan of gearboxes crammed into small guns (like G18C, DEagle, or MP7) but I got excited when I heard that some internal parts are PTW compatible. I have a long relationship with a Systema Revolution gearbox (also based on the PTW although it is not a split gearbox) and I was eager to see RWA's approach.

If you order one of these, the unit will arrive at your doorstep in double packaging --- a plain cardboard box hides the black box of the replica. Inside the box, under foam padding you can find the gun, Hop-Up adjustment tool, two magazines, manual, battery, and a leaflet about the current RWA products.

Not too many manufacturers will include two magazines with their replicas and this is a big plus in my book because this replica will most likely serve as a secondary gun and buying an extra magazine is the first thing people do after getting their secondary gun. One steel magazine holds 90 rounds so with the two magazines you can get out of any bad situation. Both included magazines sit firmly in the magwell without any wobble so the magazine can be used as forward grip if you prefer to handle your machine pistol that way. The magazine release lever is on the bottom of the magwell behind the magazine, far away to operate with your trigger hand but mag change on the KG-9 can be familiar to those who ever handled an MP5.

The manual will tell you how to connect your battery and how to attach a silencer, plus it contains the exploded view of the replica with part numbers. The leaflet shows where RWA is now: a while ago they only offered a few handgun replicas but with their ever growing list of partners now they offer BBs, batteries, internal/external parts, and serious collector items as well.

Getting the replica out of the box makes you realize how well-made this gun is. The only thing that rattles is the charging handle but that problem can be easily fixed by tightening a screw. The shape of the polymer lower was probably inspired by an M4. The quality of the lower receiver on this gun is excellent, it is not the shiny and cheap plastic that you see on some replicas.

The markings on the receiver are on the right place, with a unique RWA serial number on the magwell and Interdynamics logo on the pistol grip. The grip is fairly large, larger than an AK and M4 grip as you can see on the image below.

The upper receiver/barrel shroud is stamped steel just like the one on the real steel with evenly distributed shiny black coat. Somehow the contrast of the matte lower and shiny upper looks appealing and it's hard to imagine that I am looking at a design more than 30 years old. The gun looks more or less like the Maruzen KG-9 GBB without the folding stock and at first it's not that obvious but the barrel and the heat shield are slightly longer than the barrel of a real life KG-9. Given the design there is no other room for a battery but under the heat shield, so being longer isn't that bad after all.

The KG-9 comes with a 7.4V, 1200mAh LiPo battery which fits perfectly under the heat shield. The charging handle can be pulled back against a spring and it also locks back on the rear which serves as the safety function on the real life KG-9, but on this replica the safety can be found in the front of the trigger inside the trigger guard.

Locking back the charging handle on an AEG usually helps to adjust the Hop-Up dial but on this replica the Hop-Up can be adjusted through the magwell after removing the magazine. The end of the outer barrel can be removed and this way the replica will accept mock silencers with -14mm thread.

To access the internals (for spring change, or to lubricate parts) you need to take off the thread protector and the barrel shroud end-plate and take out the screw at the back of the gun. Additionally, you also need to remove the outer barrel so you can tilt the upper receiver enough to slide it off forward. If you tightened the barrel too much the last time around then just knock out the front body-pin and this will give you enough clearance for the upper receiver.

Taking off the barrel shroud/upper receiver will reveal what's under the hood. The upper part of the gearbox slides out of the gearbox with the Hop-Up housing/barrel. On the inside of the upper receiver you will find the screw that causes the only rattle on the KG-9, but if you tighten it you won't be able to lock back the charging handle anymore. Locking back the handle has no practical use on this replica (the Hop-Up adjustment is done through the magwell) so I just tightened mine in order to give me a better experience when handling the gun.

The Hop-Up chamber is similar to a PTW chamber but it was modified in order to fit the KG9. The shape of the rubber bucking is pretty impressive: there is a small gap right in the middle of it so each BB is forced to pass through the bucking at the same exact place, and this improves grouping a whole lot. You don't see a bucking this good in a non-custom factory replica. The tolerance between the Hop-Up housing and the upper gearbox is zero, and it's great to know that your Hop-Up chamber is not moved when you insert the magazine or when the gearbox starts pounding it from the back.

I like the way that the Hop-Up housing is fixed to the gun. In most cases the Hop-Up housing or chamber is fixed to the upper receiver but here it is fixed to the polymer lower receiver with one massive pin and the upper receiver only serves as a cover for everything that's inside the gun.

Most unique guns have terrible internals from a gunsmith's point of view, but taking apart this gun is not hard and definitely not time consuming. The KG-9 has a split-gearbox like a PTW which makes maintenance easier. Of course there are differences but the cylinder assembly is nearly 1:1 Systema and uses PTW or aftermarket parts. This is clearly visible when you take apart the cylinder assembly that sits inside the CNC aluminum upper gearbox.

I was able to spot only three things that differs from Systema parts: the material of the nozzle is stainless steel while most PTWs use plain steel nozzle, the color of the O-ring inside the piston head have bright yellow color and finally the presence of a coating on the piston rack, but none of these parts are different in form, dimension or function. The piston has a full steel tooth rack with nice coating and smaller second tooth to avoid conflicts with the sector gear. The parts are slightly lubed and the piston head's O-ring provides good seal under a compression test (manually pushing the piston while covering the nozzle).

Removing a plate on the bottom of the pistol grip will let you take out the motor. Nothing exciting here, but a standard motor with a short neck will perfectly do the job of pulling the KG-9's spring. The spring is an SP100 PTW spring and like any other PTW spring, its diameter is smaller than a regular AEG spring.

Inspecting the gearbox internals will reveal the main difference between this gearbox and a PTW's gearbox: the lack of an ECU. The cycle in a PTW is controlled by electronics and an optical sensor so you will not find anti-reversal latch or cut-off lever there, but here you can find an anti-reversal latch just like inside of any other standard AEG's gearbox.

It was either too complicated to fit Systema's ECU inside this gearbox or simply it would make the replica very expensive. The KG-9's gearbox have good quality AEG gears made of steel which are certainly cheaper than a set of PTW or Revolution gears. If you look at the front part of the gearbox you will see that the firing switch is not standard but it is a micro switch and probably this is the main reason the gun does not have semi-auto firing mode. Without the ECU, the cut-off lever is the only option to have semi-auto firing mode in an AEG but a standard cut-off lever could not interact with the non-standard firing switch so we're left with full-auto. The firing switch is activated by the top side of the trigger and it would be nice to see a piece of metal here which stops the trigger right after it activates the switch but it looks sturdy enough to handle the full weight of your finger.

The safety is mechanical instead of electrical, meaning it simply blocks the trigger when activated and I prefer this method over electrical safety (with my Revolution gearbox you are able to fully pull the trigger even in safe mode and I find this feature bothering). The fire selector on most split-gearbox AEG (without ECU) serves as "decocker" as well, releasing spring tension (usually by lifting the anti-reversal latch) when set to safe. This becomes important when you open your receiver and the piston slams forward if the cycle was not completed the last time the gun was fired. Missing such mechanism will make you mechanically set sector gear position before closing up the receiver: wrong gear alignment between the sector gear and the piston can seriously alter the interior design of a gearbox and not in a good way!

The images below will show you the correct sector gear position and it is important to check for this position before mating the upper gearbox with the lower.

After all this you might ask: who is this gun for? Well, clearly not for everybody given the nearly $438 asking price. But if you look at it from a different angle then the KG-9 might not be that expensive after all for one simple reason: you don't have to spend a dime on it for a long time. Buying a small SMG AEG usually leads to additional expenses like buying extra magazines, battery, replacing poor Hop-Up and other internal parts.

Let me give you one example assuming you're looking for something that's about the same weight and size and you don't want to use it for CQB too much: The Tokyo Marui MP5K costs about $260 and you need to purchase four additional 50rd magazines (if you don't want to rattle around with the included Hi-Cap magazine) to hold the same amount of BBs as the KG-9 with its two included mags. For the MP5K you 're going to need a battery as well and all these items will cost you about $140 on top of the $260 and if you are satisfied with the MP5K's 250FPS performance then it comes out $40 cheaper and you have a weaker gun with some rail space. Maybe my numbers are wrong but a cheap replica is cheap for a reason and if you ask me then I would take the PTW internals over the MP5K any day and not because I look down on the default Marui gearbox (I own one).

If you can deal with the fact that this replica does not have semi-auto firing mode then I can highly recommend it based on my experience. The RWA KG-9 can be nice partner of any DMR especially if you are re-enacting criminals, rebels or any non-traditional military units. It also could be nice base for a unique custom gun project: the full cylinder will let you install longer barrels underneath a mock silencer while the thick gearbox walls eliminate the worry if you fancy a stronger spring. If you could find a Maruzen folding-stock for KG-9 plus a real steel KG-9 front grip (for extra battery space) then you'd have a monster at your hands.

You will find spare parts for the KG-9 as long as there are PTWs out there. Parts are maybe a bit expensive but if you avoid prolonged use of full-auto fire, then you don't need to change anything in this gun. The firing switch seems to be something that you can find in your local electronic parts store although I did not take it out of the gun to verify the part number on it.

Funny that people wanted to convert the real life KG-9 to full-auto in order to better suit their needs and I would love to convert this to semi-auto so I can take it to a CQB game where this gun would really shine. But if you're lucky enough to have a CQB field near your location that allows burst-fire then this gun might be just right for you because controlling short bursts is very easy with the KG-9's firing switch.

I only tested the gun in short ranges where it proved to be reliable and very accurate thanks to the PTW Hop-Up system. In a PTW, if the nozzle is not aligned right in relation to the hop-up chamber then you immediately have feeding problems, jams and your nozzle will chop BBs in half sucking debris back into the gearbox. But during the time I've spent with the KG-9 I haven't had a single feeding related problem. I would be happy to tell you more about my experience but now this KG-9 is headed towards the Netherlands so SlickAxe of NLAirsoft.com and his friends can do a video review. NLAirsoft.com will show you how the gun handles in different situations and of course they will take a look at range and accuracy as well. We will give you guys a heads up as soon as they published the video.

Thanks for reading, and thanks to RWA for letting me spend time with this beauty.

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